Mechanical ventilation, both invasive and non-invasive, may be an effective means of improving the quality of life and prolonging the survival of patients suffering from amyotrophic lateral sclerosis (ALS). However, the attitude towards this palliative measure varies greatly between different centres and countries. One of the arguments cited against this procedure is the fear that a patient might request the physician to discontinue life support. We believe that the question of withdrawal of mechanical ventilation can only be meaningfully addressed in the general context of palliative care. Here, we review possible modes of action in response to a patient's request for life support withdrawal and their medical, legal and ethical implications. We propose that the following goals should be pursued: (1) prevention of unwanted ventilation by early, open discussion with patient and relatives, (2) delivery of optimal palliative care by the caring team, (3) recognition of the patient's right to withdraw his/her consent to an invasive medical procedure. If these goals have been met, it may be medically, legally and ethically justified for the physician to take all necessary steps to ensure a peaceful death after discontinuation of life support.